The present disclosure relates to semiconductor integrated circuits which include a power supply switch circuit having the function of switching power supply voltages to be supplied.
Typically, when a higher signal frequency is employed in order to provide a higher-speed interface, the signal voltage level is reduced in order to reduce the increase in power consumption. For example, while SD cards that comply with the traditional interface standard use a 3.3-V signal interface, SD cards that comply with the state-of-the-art high-speed standard use a 1.8-V signal interface. In the case of interface standards widely used such as the Secure Digital standard, devices are required to support both new and old standards, and therefore, interface circuits need to switch signal voltage levels, depending on the standard with which a connected SD card complies. Therefore, a power supply switch circuit is needed which switches a power supply voltage supplied to the interface circuit between 3.3 V and 1.8 V.